Achilles

One of Greece's strongest warriors. When he was born his mother made a deal with the gods so that her child could only be weakened if attacked on his heel. It is said that when he lost his beloved Patroclus to the Trojan army he entered an almost god-like rage as he slew entire armies before one luckily archer was able to shoot his heel killing the young warrior. However, as his spirit was entering the realm of the dead Ares sought to use the warrior as his own personal sword. So he cast a spell that amplified Achilles's rage and trapped him between realms as an undead wraith-filled specter. So Achilles lived on for years as a weapon devoid of his humanity.

This was the case until one day the party was able to use their combined might to free Achille from Are's control allowing the warrior to finally find peace in the afterlife with his beloved Patroclus.